1. Field of the Invention
The present invention relates to a bag-shaped container with a straw insert hole formed thereon which is used particularly in the form of a self-standing pouch for containing liquid such as juice or the like. Further, the present invention relates to a method of producing bag-shaped containers of the above-mentioned type.
2. Description of the Prior Art
To facilitate understanding of the present invention it will be helpful that a typical conventional self-standing pouch will be briefly described below with reference to FIGS. 1 and 2. As illustrated in the drawings, the self-standing pouch (hereinafter referred to simply as standing pouch) comprises a front surface member 2, a rear surface member 3 and a bottom member 4 and they are heat sealed to one another to such a shape that its lower part has a tubular configuration so as to allow it to stand upright by itself. Material having fludity is contained in the standing pouch to be stored or displayed. When an user wants to take the content out of the standing pouch, he is required to tear the upper part away from the body of the standing pouch by utilizing a notch 5. Then, he sucks the content through a straw or the like means. However, it has been found that a considerably high intensity of force is required for tearing operation and therefore a child can open the pouch only with much difficulties. Another problem is that there often spills content in the pouch due to vibrative movement during tearing operation. In view of the foregoing problems there has been already proposed an improved standing pouch with a straw insert hole preformed thereon but the improved standing pouch has also problems with respect to two functional performances to be achieved as a container, one of them being capability of holding of content and the other one being easiness of handling or using of the standing pouch.
An important thing to be noted when a strip of laminate sheet is employed as sheet material for producing standing pouches is that adhesive, ink or cut edge of aluminum foil are exposed along the inner periphery of a straw insert hole which is formed on the laminate sheet by punching operation. To inhibit the exposed material from coming in contact with content in the pouch there is necessity for developing a new technique. For the reason standing pouch of the early mentioned type which can satisfactorily meet the requirements is not obtained at present. To obviate this problem the inventor proposed a method of producing improved standing pouches with straw insert hole formed thereon and filed an application for patent in Japan under patent application No. 17,837/82. It has been proven that the proposed method brings remarkable improvements but a problem is kept unresolved which is related to blowing of content which tends to occur when a straw insert hole is opened with a tab removed from the body of the pouch. Thus, requests for eliminating this problem have been raised from users.